Question

What is a subquery?
एक सबक्वेरी क्या है?
Select one:
A. A subquery is a condition that
excludes all the invalid tuples from
the database
एक सबक्वेरी एक ऐसा कंडीशन है जो डेटाबेस
से सभी अमान्य ट्यूपल्स को बाहर करती है
B. A subquery is a relation that is
externally specified which can be
used to handle data in queries
एक सबक्वेरी एक रिलेशन है जो बाहरी रूप से
निर्दिष्ट है जिसका उपयोग क्वेरीज में डेटा को
हैंडल के लिए किया जा सकता है
OC. A subquery is a select-from-
where expression that is nested
within another query
एक सबक्वेरी एक select-from-where
एक्सप्रेशन है जो किसी अन्य क्वेरी के भीतर
निहित है
4
|
=​

Answer 1

• Subquery or Inner query or a Nested query is a query within another SQL query and embedded within the WHERE clause. A subquery is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved.

Answer 2

Answer:

A subquery in SQL is just a query included within another query. To put it another way, a subquery is a query that is included within the WHERE clause of another SQL query.

Explanation:

Essential guidelines for subqueries:

• The WHERE clause, HAVING clause, and FROM clause are just a few SQL clauses where you may put the subquery.
• Subqueries can be used in conjunction with expression operators and the SELECT, UPDATE, INSERT, and DELETE commands. It could be a comparison or equality operator, such as the =, >, =, =, and Like operator.
• An internal query is known as a subquery. The inner query is known as a subquery, while the outer query is known as the main query.
• The subquery typically runs first, and the results are utilised to complete the outer or main query's query condition.
• Parentheses must be used around the subquery.
• On the right side of the comparison operator are subqueries.
• In a subquery, the ORDER BY command cannot be used. The GROUPBY command serves the same purpose as the ORDER BY command.
• Use single-row subqueries with single-row operators. When using multiple-row subqueries, use multiple-row operators.